Bearing Characteristics of Diaphragm Wall Foundation under Vertical and Combined Load

To investigate the bearing characteristics of diaphragm wall foundation under combined load, the results from elasto-plastic analyses of 3D finite element models (FEM) were presented in this study. The vertical load of the diaphragm wall foundation is borne by inner and outer side resistance, resistance of soil core and the end of wall, respectively. Moreover, the sum of end resistance and soil core resistance accounts for about 75% of the vertical load. The mobilization mechanism and distribution of side resistance of the foundation were also analyzed. It is clarified that the mobilization characteristics of inner and outer side resistance of the wall are completely opposite. Due to the combined load, the horizontal load has an amplification effect on the settlement of the foundation. Additionally, the calculation methods of the Eight-component Winkler spring model and rigid pile displacement were used for determining the vertical load-bearing capacity and the overturning stability. A comparison between results from the FEM and the theoretical calculation methods showed that the results of the numerical simulation properly coincided with that of the displacement solution of theoretical model. The conclusions obtained by the above methods all indicate that the foundation has the characteristics of overall overturning failure under the combined load.

TEGAL BESAR BEACH REHABILITATION WITH SCALLOPED CONCRETE BLOCK REVETMENT

Klungkung has a coastline of 113 km out of a total of 5780.06 km2 the coastline in the province of Bali, but about 25 km is eroded. One of the critical areas occurs in Tegal Besar beach which caused erosion of 0.08875 to 3.0915 m/yr. Revetment with scalloped concrete blocks is expected to protect land from the wave attack. Concrete blocks have uniform size and shape, showing the aesthetic aspect so as not damage the beauty of the beach. Analysis of wind, tidal, bathymetry and soil data are carried out to obtain the structure and stability of the revetment. The results of this design can be used to rehabilitate the condition of the Tegal Besar beach. From the analysis, the design wave height with a return period of 25 years (H25) = 0.891 m, while the height with the breaking wave (Hb) = 1.003 m and the breaking wave depth (db) = 1.068 m and the design water level elevation (DWL) = 2.061 m calculated from MSL. The revetment structure has a height of 4.00 m, a peak width of 1.50 m, the weight of the first layer of protection is 300 kg and the second is 30 kg with a thickness of 1.00 m. Toe protection are 1.25 m high, 3.00 m wide and weigh 150 kg. The results showed that the revetment was stable against overturning, shearing, and the bearing capacity of the soil was declared safe with the results of overturning stability 22,075 > 2, slidding stability 2.249 > 1.5 and the bearing capacity of the soil 57,993 > 3 so that the revetment can be eligible to be applied at the site.

The effect of the setback angle on overturning stability of the retaining wall

Retaining walls are a relatively common type of protective structure in construction to hold soil behind them. The form of the retaining wall is also relatively diverse with changing setback angle. Design cross-selection of retaining wall virtually ensures the stability of the retaining wall depends on many aspects. It is essential to consider these to bring the overall picture. For this reason, the authors selected a research paper on the influence of the setback angle on the overturning stability of the retaining wall. To evaluate the behavior stability of retaining wall with some key factors having different levels such as setback angle, internal friction angle of the soil, the slope of the backfill is based on the design of the experiment (DOE) with useful statistical analysis tools. These, proposing the necessary technical requirements in choosing significant cross-sections of retaining structure to suit natural terrain and save construction costs, ensure safety for the project.

Overturning stability of supported geomembrane tube for flood control

As a kind of rapid filling hydraulic structure, geomembrane tube can effectively act as flood barriers and cofferdams for flood risk management. L-shaped block is used to support geomembrane tube to prevent it from rolling. The contact force between the L-shaped block and the geomembrane tube is analyzed by using particle flow code (PFC2D) software, and the overturning stability of the L-shaped block is calculated. The relationship between the key factors and the overturning stability was established. It is found that the central angle of the L-shaped block has little influence on the overturning stability. The overturning stability decreases with the increase of the initial pumping pressure. Keeping Lw/Lb unchanged, increasing Lb will improve the overturning stability where Lw and Lb are the width and the height of the Lshaped block. Under the ultimate water level, when 1.23 Lbcr < Lw≤1.55 Lbcr, the L-shaped block is in the state of overturning stability where Lbcr is the critical height of the L-shaped block. The initial pumping pressure is less than 0.152γL, the L-shaped block is in the state of overturning stability with Lw/Lbcr =1.0 where L is the cross-sectional perimeter of the geomembrane tube and γ is the unit weight of the filling liquid, on the contrary, Lw/Lbcr must be greater than 1 to ensure its overturning stability.

DESAIN SABO DAM TIPE CONDUIT SEBAGAI PENGENDALI DAYA RUSAK ALIRAN DEBRIS

ABSTRAKSungai Air Kotok di Kabupaten Lebong, Bengkulu memiliki litologi batuan yang rapuh akibat pengaruh panas bumi, kondisi tersebut menyebabkan rentan mengalami pergerakan massa tanah/batuan. Oleh karena itu, diperlukan upaya mitigasi untuk mengurangi risiko bencana dengan perencanaan bangunan pengendali aliran debris berupa sabo dam. Penelitian ini bertujuan untuk merencanakan desain sabo dam tipe conduit yang dirancang secara seri dan mengevaluasi stabilitas sabo dam berdasar SNI 2851:2015. Hasil perhitungan menunjukkan debit puncak untuk kala ulang 100 tahun sebesar 171,21 m3/detik. Empat seri sabo dam memiliki dimensi lebar pelimpah rerata ± 40 m, kedalaman aliran debris sebesar 1 m, dan tinggi pelimpah ialah 2,4 m. Stabilitas sabo dam saat banjir diperoleh faktor aman untuk stabilitas geser dan guling sebesar 3,46 ; 1,62. Adapun faktor aman terhadap pengaruh aliran debris untuk stabilitas geser dan guling adalah 3,30 ; 1,58. Berdasarkan hasil analisis, empat seri sabo dam tipe conduit yang dirancang mampu mengendalikan daya rusak banjir maupun aliran debris.Kata kunci: Hidraulika sungai, aliran sedimen, bangunan sabo, stabilitas sabo ABSTRACTAir Kotok River in Lebong Regency, Bengkulu Province has the lithology of weathered rock which is a result of geothermal process, this condition causes to be susceptible to land / rock mass movements. Therefore, the mitigation efforts are needed to reduce the risk from disaster by design debris flow control such as sabo dam. This study aims to design series of conduit type sabo dam and evaluate the stability based on SNI 2851: 2015. The calculation shows that the peak discharge for the 100-year return period is 171.21 m3 / sec. The four sabo dam series have dimensions of spill width of ± 40 m, debris flow depth of 1 m, and overflow height of 2.4 m. The stability of sabo dam has safety factor in flood condition for shear and overturning stability are 3.46; 1.62, while in a debris flow condition for shear and overturning stability are 3.30; 1.58. Based on the results, the four series of conduit sabo dam are able to control the destructive power of floods and debris flows.Key word: River hydraulic, sediment flow, sabo building, stability of sabo

Numerical Analysis of Vertical Breakwater Stability under Extreme Waves

The purpose of this study is to perform a numerical simulation of caisson breakwater stability concerning the effect of wave overtopping under extreme waves. A numerical model, which solves two-dimensional Reynolds-averaged Navier–Stokes equations with the k−ε turbulence closure and uses the volume of fluid method for surface capturing, is validated with the laboratory observations. The numerical model is shown to accurately predict the measured free-surface profiles and the wave pressures around a caisson breakwater. Considering the dynamic loading on caisson breakwaters during overtopping waves, not only landward force and lift force but also the seaward force are calculated. Model results suggest that the forces induced by the wave overtopping on the back side of vertical breakwater and the phase lag of surface elevations have to be considered for calculating the breakwater stability. The numerical results also show that the failure of sliding is more dangerous than the failure of overturning in the vertical breakwater. Under extreme waves with more than 100 year return period, the caisson breakwater is sliding unstable, whereas it is safe in overturning stability. The influence of wave overtopping on the stability analysis is dominated by the force on the rear side of the caisson and the phase difference on the two ends of caisson. For the case of extreme conditions, if the impulse force happens at the moment of the minimum of load in the rear side, the safety factor might decrease significantly and the failure of sliding might cause breakwater damage. This paper demonstrates the potential stability failure of coastal structures under extreme sea states and provides adapted formulations of safety factors in dynamic form to involve the influence of overtopping waves.

Adaptive Frame of Universal Vehicle Course

Background: Motor vehicles play an important role in the economies of many countries, providing efficient means of transporting goods and people. These vehicles can also have significant impacts on safety, infrastructure and the environment. Methods: The design of the suspension affects the vehicle's performance, in terms of the drive, damage to infrastructure, the working space of the suspension, power, and stability against overturning, stability against yaw, braking, and traction. Results: The article considers the types and methods of application of adaptive suspensions of modern vehicles, justifies the feasibility of their use for various vehicles, such as modern cars, tractors, etc., which allows the usage of these vehicles for traffic in different road conditions - mountainous terrains with a slope of more than 35o, steppe off-road conditions with frontal obstacles up to half the length of the wheel radius. Conclusion: The existing control schemes and prospects for their further development can be improved and intelligent transport systems could be introduced.

Analysis of Overturning and Vibration during Field Operation of a Tractor-Mounted 4-Row Radish Collector toward Ensuring User Safety

The overturning stability and vibration of upland crop machinery under development are important issues for analysis because farms for upland crops are usually uneven, which may cause work-related fatalities, and vibration affects user comfort and reduces the durability of components. In this study, the overturning stability and vibration of a tractor-mounted radish collector were investigated to ensure safety during radish collection. To analyze lateral stability, the center of gravity (CG) of the tractor-mounted radish collector system was calculated mathematically. Then, a simulation was performed to determine the lateral overturning angles at different folding positions of the radish conveyor belt and load conditions, and the results were validated through tests. Vibration sensors were used to measure the vibration levels and the power spectrum density (PSD) was obtained to check the cyclic apparatuses of the major frequencies. The load conditions, different conveyor speeds, and locations were considered as factors affecting the vibration levels. Considering the physical parameters of the tractor–collector system, the analytical overturning angle was 30.5°. The average overturning angle difference between the simulation and validation was 5°, and the difference between loaded and unloaded conditions was 2°. For 0, 45, and 90° folding positions of the conveyor belt, overturning angles increased and varied from 0.5 to 1°. The vibration level was greater under the unloaded conditions and increased with an increase in the conveyor speed. Vibrations under the loaded condition (0.37~0.48 ms−2) satisfied the ISO (International Organization for Standardization) standard (except the first conveyor belt). According to the PSD analysis, high magnitude peaks (>25 dB) appeared frequently in all directions, which indicates a high possibility of damage to the first conveyor belt. This study provides useful information for improving the safety and durability of agricultural machinery for uneven and sloped field conditions.

System Stability of Bored Piles with Steel Supports for Deep Foundation Pits in Sandy Pebble Stratum

Background: At present, there is few researches on the stability of the supporting structure of bored piles with steel supports for deep foundation pits, and it is even less common to use this support method for deep foundation pits in sandy pebble stratum. This paper studied the stability of the deep foundation pit support of the Southwest Jiaotong University Station in Chengdu, China, using the stability analysis theory of bored piles with steel supports for deep foundation pits Objective: The study aims to show the stability of steel supports for deep foundation pits Methods: The overall stability, anti-overturning stability and uplift stability of the foundation pit are important components of the stability analysis of bored piles with steel supports for deep foundation pits. Aiming at the designed method and parameters of the bored piles with steel support for the deep foundation pit, an in-depth theoretical analysis and calculation of the overall stability, anti-overturning stability and uplift stability of the deep foundation pit is conducted respectively Results: The results show that the stability of the deep foundation pit using bored piles with steel support meets the requirements, meaning the design of this support form is safe and reasonable, thus ensuring the smooth progress of the project. Conclusion: The stability analysis of deep foundation pits in sandy pebble stratum provides ideas for the optimization of deep foundation pits and a reference for the stability analysis of deep foundation pits in sandy pebble stratum and other types of stratum.